11th ICRS Abstract book - Nova Southeastern University

Oral Mini-Symposium 10: Ecological Processes on Today's Reef Ecosystems
10-9
Importance of Post-Settlement Mortality on Scleractinian Population Maintenance
around Moorea, French Polynesia
Lucie PENIN* 1,2 , Francois MICHONNEAU 1,2 , Andrew H BAIRD 3 , Sean R
CONNOLLY 3,4 , Morgan S PRATCHETT 3 , Mohsen KAYAL 1,2 , Mehdi ADJEROUD 1,2
1 Université de Perpignan, UMR CNRS EPHE UPVD 5244 Biologie et Ecologie
Tropicale et Méditerranéenne, Perpignan, France, 2 UMS CNRS 2978, CRIOBE,
Papetoai, French Polynesia, 3 ARC Centre of Excellence for Coral Reef Studies, James
Cook University, Townville, Australia, 4 School of Marine and Tropical Biology, James
Cook University, Townsville, Australia
At a fundamental level, spatial variation in the abundance and community structure of
scleractinian corals must be influenced by patterns of larval settlement. However, spatial
variation in early post-settlement mortality has the potential to greatly distort patterns
established at settlement, and the relative influence of variation in settlement rates and
post-settlement processes on spatial dynamics of coral assemblages remains largely
unknown.
In this study, spatial variation in mortality of recruits (< 3 months of age) and juvenile
corals (< 5 cm in diameter; ~1-4 years of age) was quantified in three depth zones at each
of three locations and round Moorea, French Polynesia. Mortality of coral recruits was
extremely variable and particularly high (50 % in 7 days), and is associated with the
abundance of parrotfishes (Fam. Scaridae). Juvenile mortality was less intense (up to 40
% in 14 months), but also shows strong spatial variability, corresponding with variation
in abundance of butterflyfishes (Fam. Chaetodontidae).
Spatial variability in early post-settlement mortality partly accounts for apparent
differences in the abundance of coral recruits versus juveniles corals, highlighting the
potential importance of post-settlement processes as a driver of spatial variation in the
dynamics of coral assemblages. Moreover, variation in early-post settlement mortality of
corals appears to be influenced mainly by local densities of Scaridae and Chaetodontidae,
which each affect a different stage in the life-cycle (recruits versus juvenile corals,
respectively).
10-10
Reproductive Demography Of siderastrea Radians in The St. Martins Keys,
Florida
Katherine LAZAR* 1 , Thomas FRAZER 1 , Charles JACOBY 1 , Colette ST. MARY 2
1 Department of Fisheries and Aquatic Sciences, University of Florida, Gainesville, FL,
2 Department of Zoology, University of Florida, Gainesville, FL
The reproductive demography of corals plays a significant role in their population
dynamics by influencing reproductive success. The objectives of this study are to
quantify spatial variation in: 1) density, 2) size distribution, 3) fertility, and 4) sex ratio in
a population of Siderastrea radians in the St. Martins Keys, Florida. Initially, corals were
counted and measured in 10 quadrats placed at random points along one randomly
oriented, 25-m transect at each of 81 sites arrayed in a 16-km2 grid. Results from the
survey indicate that corals were distributed in patches (mean Morisita Index = 5.98; range
= 0−20), with densities ranging from 0.0 to 86.0 individuals m–2 (mean = 7.0 individuals
m−2). The size-frequency distribution was typical of other scleractinian populations, with
the majority of individuals falling within the smallest size classes (positive skew). A
statistically significant linear regression showed that numbers of individual polyps, i.e.,
recruits, increased with numbers of putative adults (p < 0.001). To quantify the
relationships among density, aggregation, and sex ratio, corals were collected from 10
sites with different combinations of density and aggregation (i.e., high density/low
aggregation, medium/low, low/low, low/medium, and low/high). Preliminary histological
data corroborates previous reports of a female-biased sex ratio in this species. Overall,
results point to the potential importance of small-scale, demographic patterns in
determining the reproductive success and population dynamics of S. radians.
10-11
Survival Dynamics Of Azooxanthellate Scleractinian Coral Larvae And Implications For
Dispersal
Erin GRAHAM* 1 , Andrew BAIRD 2 , Sean CONNOLLY 3
1 School of Tropical and Marine Biology, James Cook University, Townsville, Australia, 2 ARC
Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Australia,
3 ARC Centre of Excellence for Coral Reef Studies, and School of Tropical and Marine Biology,
James Cook University, Townsville, Australia
Survival of pelagic marine larvae is an important determinant of dispersal potential. For
scleractinian corals, however, few studies of larval survival are long enough to provide accurate
estimates of longevity. Moreover, changes in mortality rates during larval life have
implications for connectivity among reefs and have not been quantified for any coral species.
This study quantified the survival of larvae from five scleractinian corals (Acropora latistella,
Favia pallida, Pectinia paeonia, Goniastrea aspera, and Montastraea magnistellata) to
estimate larval longevity and test for changes in mortality rates as larvae age. Maximum
lifespans ranged from 195-244 d, substantially exceeding those documented previously for
azooxanthellate corals and predictions based on metabolic rates. In addition, larval mortality
rates exhibited strong patterns of variation throughout the larval stage. Three periods were
identified in four species: high initial rates of mortality; followed by a low, approximately
constant rate of mortality; and finally, increasing mortality after approximately 100 d. The
observed lifetimes suggest the potential for long-distance dispersal may be substantially greater
than previously thought, probably because larvae regulate their energy use. Indeed, detection of
increasing mortality rates late in life suggests that energy reserves do not reach critically low
levels until approximately 100 d. Conversely, increased mortality rates early in life decrease
the likelihood that larvae transported away from natal reefs will survive to reach nearby reefs,
and thus decrease connectivity at regional scales. These results show how variation in larval
survivorship with age may help to explain the seeming paradox of high genetic structure at
metapopulation scales, coupled with extensive geographic ranges, observed in many coral
species.
10-12
The Effect Of Ultraviolet Radiation On Different Stages Of The Life Cycles Of Mass
Spawning And Brooding Scleractinian Corals
Anastazia BANASZAK* 1 , Ana Laura GARCÍA LÓPEZ 1 , Braulio AVILA RAMÍREZ 1
1 Photobiology, Universidad Nacional Autónoma de México, Puerto Morelos, Mexico
Ultraviolet radiation (UVR, 280 to 400 nm) is an important physical factor affecting shallow
water reef communities. The effect of ecologically relevant doses of UVR was determined on
different stages of the life cycle of the reef-building corals Montastraea faveolata and Acropora
palmata, both summer mass-spawning species, as well as on Favia fragum, a species that broods
larvae to the planula stage and releases them on a monthly basis. Four different earlydevelopment
life stages (blastula, gastrula, non-motile planula and motile planule) of
Montastraea and Acropora were exposed to artificial solar UVR that was equivalent to a one
day dose of natural solar radiation. The gastrula was found to be the most sensitive life cycle
stage of Acropora whereas all stages of Montastraea were equally sensitive as determined by
mortality during exposure to UVR in comparison to larvae exposed without UVR. Postexposure
mortality rates also differed, with the Acropora planula and Montastraea motile
planula being the most sensitive of the four stages. Due to their small size and monthly
reproduction, Favia colonies are more amenable to experimental manipulation. Favia colonies
were exposed to natural levels of solar radiation over a 13 month period. Colonies in treatments
with UVR filtered out produced 9 times as many larvae as colonies exposed to UVR. The larvae
that were produced exhibited significantly higher mortalities during exposure to UVR as did
juveniles when compared to exposures without UVR. Settlement rates, sites and preferences
were also affected in the presence of UVR. Our date show that UVR is an important physical
factor in the life cycle of mass spawning and brooding reef corals and should be considered in
discussions on reef connectivity and ecology.
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